1. Field of the Invention
The present invention relates to an on-board navigation apparatus which displays navigational information from the present location of a vehicle to a destination.
2. Description of the Related Art
There is an on-board navigation apparatus known which has map information including road data acquired by digitization of individual points on roads or streets on a map stored in a storage medium such as a CD-ROM, reads from the storage medium a group of map data of a certain area containing the present location of a vehicle, while tracking the present location, and shows the data as a map around the present vehicle location on a display as well as automatically displays the present vehicle location on the map. The type of prior art is disclosed in, for example, Japanese Provisional Patent Publication No. 63-12096.
This on-board navigation apparatus computes the direction and distance as navigational information from the present location to the destination in accordance with the outputs of sensors such as a direction sensor and a distance sensor to display the information on a display. The destination data is input by key operation of a user such as the driver to be stored as destination coordinate data in a memory. As long as this destination coordinate data is present in the memory, the direction and distance from the present location to the destination can be computed in accordance with the destination coordinate data and displayed on the display. When the distance from the present location to the destination becomes equal to a predetermined value or smaller while the vehicle is running, however, it is judged that the vehicle has arrived at the destination so that the destination coordinate data will automatically be erased from the memory, and the direction and distance will no longer be displayed. The conventional navigation apparatus therefore requires a complicated key operation even when the same destination as the previous one is to be set as a new destination.